gtk theme switching

i saw online that there were gtk themes, themes that change most program's appearance...
to change a theme:
download a theme here
su
mv foo.tar.gz /usr/share/themes
tar -xvzf foo.tar.fz
su user
cd
edit .gtk-2.0 like this:
# -- THEME AUTO-WRITTEN DO NOT EDIT
include "/usr/share/themes/Tenebrific/gtk-2.0/gtkrc"

include "/home/tuxxman/.gtkrc.mine"

# -- THEME AUTO-WRITTEN DO NOT EDIT